The most common and most likely answer to this crossword clue is the 6 letter word MOLEST
M
O
L
E
S
T
More clues leading to the result MOLEST
- Secret agent, good person in trouble
- Harass spies beginning to turn
- Sleepers finally resent abuse
- Harry plants last of mint
- Spy on street creating trouble
- Harry spots Tory leader
- Attack underground workers heading for tunnel
- Trouble created by furry creature on street
- Harry spies gent issuing dope
- Interfere with doctor in case
Buddy explains!

The straight part
We know that "Upset" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case upset = molest.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does MOLEST mean?
MOLEST verb- To annoy intentionally.
- To disturb or tamper with.
- To sexually assault or sexually harass, especially a minor.